flush problems on american standard wall hung toilet with tank.

1983 what looks like American Standard wall hung toilet is slow to flush. The new ones keep mentioning power assist, mine has standard fill tube and flap as in any toilet. I have checked, holes under rim they are clear, cant see or feel the bottom tube from tank to check, poured water 3 1/2 gallons from bucket with same result of slow. Properly vented on 3 inch wall waste line. Do you think this had an assist flush of some sort and a homeowner put regular parts in it? My guests always complain and it takes 2 to 3 five gallon flushes to clear waste. No name under top or tank back other than a the word "waterline" , 4.9 and a number 9248. Help?

Can't help you on most of this, but one thing I can tell you is that if this was a pressure-assist bowl, it would basically not flush at all if the homeowner tried to put in a flapper and fill valve. The bowls are a very different design. We had a member here try that to make a flushmate-type toilet more quiet, and the result was that when he flushed, the thing made a slight gurgle and basically no water drained from the tank.

The current AS Glenwall apparently flushes pretty well with the pressure-assist, and is relatively-easy to install.